Low-energy extreme-ultraviolet spectroscopy of Ru IV to Ru VIII using an electron beam ion trap

Astronomical observations of elements heavier than iron in stars are very crucial to understand stellar nucleosynthesis. Elements produced by the slow neutron-capture process, commonly known as the s-process, are particularly interesting in that respect because they provide information on the time-scales involved in the process. Ruthenium is among these elements. However, a direct identification of such elements is still not possible since wavelength positions cannot be computed precisely. Therefore, laboratory measurements are crucial to overcome this problem. In this thesis, measurements using an electron beam ion trap device were carried out. Using very low electron beam energies ruthenium ions in the charge states from Ru+3+ to Ru+7 were produced. The fluorescent emitted by these excited ions was recorded using a flat-field grazing incidence spectrometer in a wavelength range of 15nm to 24 nm. The experimental data unveiled a number of fluorescent lines from ruthenium ions. The line positions and relative intensities were accurately extracted. These data may help to benchmark various theories which further may help to build precise astrophysical models to identify trans-irons lines from the stars